1. Field of the Invention
The present invention relates to a method of preparing diarylchlorophosphate for use as an intermediate for medicines, agricultural chemicals, etc.
2. Discussion of the Background
Hitherto, diarylhalophosphate has been known as an organic phosphorus compound which may be used as an intermediate for medicines or agricultural chemicals, resin additive materials, or the like. Various methods for preparing diarylchlorophosphate have been disclosed including, for example, a method (1), disclosed in Japanese Patent Laid Open No. 2-503084 (KOHYO), in which alkyldiarylphosphate is halogenated using, for example, chlorine; and method (2), disclosed in Japanese Patent Laid Open No. 5-1084, in which alkyldiarylphosphate is reacted with phosphorus pentachloride.
However, in the aforementioned method (1), since the alkyldiarylphosphite contains trivalent phosphorus, it has poor stability, and may be oxidized. In addition, only solvents which do not react with halogens, such as carbon tetrachloride or chlorobenzene can be used. Thus, it cannot be advantageously used for industrial purposes.
In method (2), phosphorus pentachloride is a solid also having sublimating properties, which not only make it difficult to handle when reacted with alkyldiarylphosphate, but also give rise to such problems as the generation of impurities as a result of secondary reactions, etc.
To overcome such conventional problems as those described above, the present invention aims at providing a method of preparing diarylchlorophosphate having high purity at a high yield, which can be advantageously used for industrial purposes.